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T O P I C R E V I E W

mach3valkyrie

Today marks the 40th anniversary of the last Saturn V rocket to fly. Launch occurred at 1:30 pm eastern time, boosting the Skylab Workshop into orbit and setting the stage for three manned crews to occupy the laboratory at different times until February 8, 1974.

I remember watching the launch on TV, staying home from school to do so, but I'm glad I did.

stsmithva

Thank you for pointing this date out. I think I'll view footage of that specific launch, and think of a couple of other ways to appreciate that massive work of engineering art.

Ronpur

I have been watching footage of this launch as much as I can the last week or so. When exactly did the shield separate from the workshop? And when did NASA find out? I wondered if it would have been visible during the launch, but the video makes it look like the clouds would have hidden it. I assume they would have gotten telemetry almost immediately, but I never hear a mention of it during launch commentary.

mach3valkyrie

The micro meteoroid shield was torn off passing through Max-Q, about 1 minute 20 seconds after launch, taking one solar wing with it and fouling the other with debris so it wouldn't deploy on orbit. Telemetry told controllers something had happened, but the public wasn't told until after orbit was achieved, and then no details until Pete Conrad described the scene upon rendezvous.

I have no doubt had the launch taken place on a clear day, tracking cameras would have captured the events. Too bad.

Ronpur

At 1:20, yep, it would have been seen. I wonder if recovery of the debris was ever tried. Skylab could have been such an expensive failure, but all of the hard work to recover made it such a huge success. I wish Spacecraft Films had done a set for it.

MarylandSpace

What launch vehicle did Skylab missions 2, 3, and 4 use?

Robert Pearlman

The crewed Skylab missions were launched on Saturn IB rockets.

mach3valkyrie

I agree. It was a great save.

Spacecraft Films has stated for quite a few years now that a Skylab DVD set was in the works. It's been pushed back many times in favor of other mission releases. In their blog, it says it's such a massive amount of material to cover that it will probably be a 6 disc set.

I'd like to see a lot smaller highlights version released now (maybe 2 discs) with a greatly detailed version later. I think sorting through all the on board stuff is what's slowing this release way down.

Dwight

I have been compiling all the Skylab footage I have and my incomplete TV downlinks alone comprise 50 hours worth. The 16mm footage probably adds another two hours at least. All the various Status Reports and mission summary films make up another three hours.

There is a lot of footage and it isn't easy to find.

tfrielin

quote:Originally posted by Ronpur:At 1:20, yep, it would have been seen.

I was there for the Skylab launch and it was, sadly, visible for only maybe thirty seconds before it pierced that low cloud deck and we never saw it again. Sure heard it though — for about a minute you could barely hear what the person next to you was saying.

If it had been a clear day, the tracking cameras would have captured the peeling away of the micrometeorite shield, just as it captured the SLA panel separating on Apollo 6 in 1968.

I seem to remember that the solar panel that was lost made it into orbit and was then ripped off by the separation rockets from the S-II stage, but I'll have to look that up to make sure.

We were in the Visitor's Center after the launch and heard on the squawk box soon after launch about the stuck panel and the heating problems.

Tom

Were you viewing from the press site?

tfrielin

No, we were in front of the VAB — about three miles distance from Pad A.

My friend and I happened to be standing at the Crawlerway next to two senior guys who worked building Skylab and who had earlier worked on the LEM.

After the launch (and ignorant of the problems) he and his family shared a couple of Budweisers with me and my friend right there in front of the VAB.

Quite a day.

Ronpur

I suppose the shield could have been recovered then, but really, what would have been the point? Skylab B was not going to fly, so it isn't like it was necessary to find out why it happened to fix it for the next flight. The priority was to fix the station on orbit for crews to visit.

If the solar panel was not lost until S-II separation, it burned up. If only it had been a clear day, the video would have been interesting!

I did watch some YouTube of the launch with ABC. I found it amazing to see the Vietnam POW who was their guest at the launch. It never occurred to me that they never learned about the Apollo landings until months after.

Blackarrow

Having dug my 1973 diary out of storage, I note that the first time I saw a spacecraft which contained astronauts was on 30th December, 1973. It was, of course, Skylab, and a short time earlier I saw the spent S II stage.

On 27th June, 1973, alerted by a newspaper report with sighting details I saw a train of four bright objects passing rapidly from west to east (from memory about 30 degrees above the horizon). I looked again 90 minutes later and saw (I assume) the same four objects passing over again.

A week later, on holiday in Austria, I cut a small article from a local newspaper headed "Was fliegt hinter Skylab her?" (What is flying behind Skylab?) The answer, according to the Bochum Observatory in Germany, was the lost solar wing and the S II stage. Elsewhere I also saw references to sections of the metal shroud which encased the upper part of Skylab during launch. Whatever the precise nature of Skylab's "entourage" those were some of the most memorable satellite sightings I have ever experienced.

tfrielin

quote:Originally posted by Blackarrow:was the lost solar wing and the S II stage

Correct — my memory (for a change) was/is correct: There is a NASA Investigation Board Report that confirms what I remember that the one (lost) solar panel did ride into orbit, only to be ripped off Skylab by the exhaust of the S-II stage's retrorockets.

Don't know when it might have reentered, but the big S-II stage came down in January of 1975.

Ronpur

I just read of another anomaly during this launch. The interstage between the S-1C and S-II did not separate from the S-II, forcing it to burn longer.

ilbasso

One thing that is not well known is that we came perilously close to losing the vehicle on the Skylab 2 launch of Pete Conrad's crew.

The vehicle's ground power "launch bus" was powered off at launch commit, as per the standard procedure. The magnetic relay to shut off ground power, instead of opening all the way, unexpectedly closed again due to residual magnetic forces in the contactor. The fact that this connector was still on, when it and all its connections were supposed to be off, created a sneak circuit through the "Thrust Failure" circuitry. The engines were at full power and the vehicle was just starting to move at this point. The "Thrust Failure" condition was supposed to shut down the launch vehicle's internal power and restore the connection to ground power. However, since the vehicle was fully powered up and starting to move, the ground power would have been severed just after the internal power had been disconnected. There would have been a complete loss of electrical power on the launch vehicle while the engines were running and the vehicle was in the air!

Fortunately, the vehicle's motion severed the electrical connection just as it was sending the command to shut down the power. Had that connection remained intact a few milliseconds longer, the history of Skylab would have been very different.

NASA engineers did not realize this had happened until they were analyzing the DEE-3 printouts of the launch events a few days after the launch.

tfrielin

quote:Originally posted by Ronpur:I just read of another anomaly during this launch. The interstage between the S-1C and S-II did not separate from the S-II, forcing it to burn longer.

Yes — the S-II interstage failed to separate due to some damage caused by the micrometeoroid shield failure. The aforementioned report is a little vague on the details, but only half the linear shaped charge fired, so the skirt stayed attached and rode all the way in to orbit. The J-2 engines experienced higher operating temperatures as a result and the engines had to burn only .7 seconds longer to compensate.

But, once again the conservative design of the Saturn V saved the day, and, even with these launch anomalies, Skylab made it into orbit. It was one good rocket.

Blackarrow

This discussion leads me to wonder whether anyone in NASA at any point sat down and asked themselves: "Hang on a minute! We're planning to put an S II stage, complete with five big heavy rocket engines, into orbit, with no idea when or where it will re-enter. Isn't that a bit risky?"

Skylab was supposed to stay in orbit long enough for a shuttle crew either to give it a re-boost or a planned re-entry, but the 33-foot diameter S II (weighing around 100,000 pounds with interstage and residual fuel) was always going to have an unplanned re-entry.

Tom

Where did the S-II stage re-enter?

tfrielin

quote:Originally posted by Blackarrow:This discussion leads me to wonder whether anyone in NASA at any point sat down and asked themselves: "Hang on a minute! We're planning to put an S II stage, complete with five big heavy rocket engines, into orbit, with no idea when or where it will re-enter. Isn't that a bit risky?"

When I was researching my Skylab B article for Quest magazine I remember coming across a NASA document in which they discuss just that. I can't recall the details after all these years, but it considered and rejected options for a retrorocket for Skylab and/or the S-II and relied on the small statistical chance of the S-II coming down over a populated area. They used the recent reentry of a Pegasus satellite as an exemplar as I recall--a rather large, heavy satellite that caused no damage when it came down, so armed with that, they rolled the dice, deciding the S-II would come down, chances are, over water.

Skylab, of course, they thought would stay up there until the Shuttle could deal with it, either boosting it higher, or de-orbiting it. But we know how that story turned out.

Having said that, NASA did de-orbit the last four S-IVB stages from Skylab and ASTP, by means of a propulsive retrograde venting of the residual fuel on-board, dumping them into the Pacific.

So why didn't they do the same for the S-II, you ask? Because the S-IVB had two things the S-II didn't have: an Auxiliary Propulsion Unit for attitude control and the Instrument Unit for command and control, giving ground controllers the ability to command the maneuver.

In contrast, once the S-II separated from Skylab, it was just a a big, seventy nine thousand pound, inert cylinder with no attitude control or communications capability. It was from that point on a derelict, destined for its inevitable uncontrolled reentry in January 1975.

Fra Mauro

It's suprising that no one thought that the shield or the panels might get damaged during launch.

Jay Chladek

Apparently, the micrometeoroid shield failure was a deal where Marshall apparently didn't test the micrometeoroid shield thoroughly enough as it was treated (at least on paper if I understand it correctly) more as a modification to a rocket stage rather than a critical manned spacecraft system. So the design didn't get the engineering scrutiny it should have gotten.

Ultimately what happened was trapped air between the shield and the surface of the lab expanded until the shield lifted up enough to get pulled away by the slipstream. Although not all of it probably went as it was likely a portion of the shield that stayed anchored to the solar wing and got hooked on the S-II stage. So when the S-II separated... remaining bits of the shield's metal structure pulled the solar wing with it.